1. Field of the Invention
The present application relates to an optical element and an optical module, and particularly relates to a light guide plate and a light source module.
2. Description of Related Art
Generally speaking, light source modules may be divided into direct-type light source modules and edge-type light source module according to different positions where the light source is disposed. Taking an edge-type light source module as an example, the light source is usually disposed at a side edge of the light guide plate, which makes light beams emitted from the light source enter the light guide plate from the side edge of the light guide plate.
In the edge-type light source module, two prism sheets and two diffusers are usually disposed on a light emitting surface of the light guide plate to increase luminance as well as uniformity of light emission. However, due to factors such as materials or surface properties of the optical sheets, the optical sheets tend to absorb or scatter a part of the light beams and consequently result in loss of light quantity to a certain extent. Therefore, the optical efficiency of the light source module is unable to be improved effectively. In particular, when the light beams are transmitted to the prism sheets, parts of the light beams are unable to be used effectively due to Fresnel reflection. Thus, how to effectively improve the optical efficiency is certainly an issue for the researchers in this field.